Currently, a system which supports a teleconference in which a plurality of users participate is utilized. For example, a system which displays images illustrating communication sessions between users participating in a teleconference on a graphical user interface (GUI) is suggested. Upon receiving an input of a contact destination by one of the users, the system dials a phone number of the contact destination, and adds an image illustrating a communication session corresponding to a user of the contact destination on the GUI.
There is also a call server which provides a feature called an enhanced whisper feature that enables a user telephonic device to simultaneously participate in different telephonic communication sessions while isolating audible input of the user between the telephonic communication sessions.
Related techniques are disclosed in, for example, Japanese Laid-open Patent Publication No. 2011-40036 and Japanese Laid-open Patent Publication No. 2007-143144.
For example, using a transfer device which transfers audio data, which is transmitted from a terminal, to another terminal, discussion by a plurality of users respectively using the terminals may be realized by outputting audio data of a voice emitted by a user of a terminal at other terminals.
While more than two users participate in a discussion, there is a case where a first user wants to attentively listen to a voice of a second user. However, when all pieces of audible input at the other terminals are output at a terminal which the first user uses, the first user may hear not only the voice of the second user but also voices of users other than the second user. For this reason, there is a problem that audio perceptibility of the voice of the second user for the first user decreases.